Kate McGough is a reporter for the British Broadcasting Corporation.
Girls don't take physics at A-level because they think it's only for white boys.
Prof Dame Athene Donald said that no mention of female scientists in the national curriculum contributes to the message society gives to discourage girls from picking physics.
She said that if you are black or female, you don't see yourself fitting in.
In the year 2021, 23% of physics A-level entrants were female.
This is the same as previous years.
Prof Donald, from the University of Cambridge, told the Commons Science and Technology Committee that most of the images one sees of scientists, physicists, are white males.
She said that teachers should counter messages from wider society that may discourage girls and children of ethnic minorities from certain subjects.
I know a lot of women in my generation who would have loved to do sciences at A-level, but their school discouraged them. I don't expect that still to be true, but there is a difference between discouragement and encouragement.
The panel session came after a government adviser was criticized for saying girls avoid physics because of its hard math.
The social mobility adviser and head teacher said that physics was not a subject for girls and that they didn't like it.
The IOP said it was alarmed by the comments, and later Ms. Birbalsingh said her language had been "clunky".
Prof Donald said that the gender balance of subjects could be tracked by the inspector to encourage girls to choose physics at A-level.
If gender equity was an issue, every school would have to think about what they were doing in primary school, and how they were giving boys different games to play.
In response, Dr Jasper Green told the committee that school inspectors were already addressing how to improve girls participation in science and math, and that they were focusing on the quality of education, on early education, on subjects.
He said that gender balance could become something that could be assessed in the future, but that there were challenges in both measuring and improving it.